The present invention relates to ferrimagnetic oxides having a low curie temperature, not oxidized and not corroded, thus the magnetic characteristics thereof being not deteriorated, and capable of allowing recording and reproducing of information or data by application of laser beams thereto when used in a magnetic film layer of a magneto-optical recording medium, and to a magneto-optical recording medium including a perpendicular magnetic-anisotropic magnetic film layer comprising one of the ferrimagnetic oxides.
Conventionally, magneto-optical recording mediums having an amorphous magnetic layer are known. The amorphous magnetic layer is easily oxidized, and if it is oxidized, the magneto-optical characteristics thereof are significantly deteriorated. Therefore, it is necessary to provide a protective layer for protecting the amorphous magnetic layer immediately after the formation of the magnetic layer. However, it is extremely difficult to prepare a protective layer completely free from pin holes.
Furthermore, when producing the magnetic film layer, a relatively large amount of oxygen still remains in a chamber for fabricating the magnetic film layer and the oxygen enters the magnetic film layer, so that the magnetic film layer is oxidized by the oxygen. Such oxidization is accelerated by the application of light and heat at the time of recording and reproducing data or information. As a result, the magneto-optical characteristics thereof are deteriorated.
A hexagonal-system M-type ferrite has been investigated for use as a magnetic bubble material as being a magnetic material free from deterioration by oxidation. This material, however, has a curie temperature as high as 450.degree. C. or more, so that it cannot be used as a magneto-optical recording material for recording by application of laser beams thereto.